AlGu pattern generation on 3D structured wafer using multi level exposure method on electrodeposited polymer material

摘要

Normal photolithography tools have focal depth limitations and unable to meet the expectations of high resolution photolithography on highly topographic structures.This paper shows a cost effective and promising technique of combining two different approaches to achieve critical dimensions of traces on slope pattern continuity on highly topographic structures.Electrophoretically deposited photoresist is used on 3-D structured wafers.This photoresist coating technique is fairly known in the MEMS industries to achieve uniform and conformal photoresist films on 3D surfaces.Multi step exposures are used to expose electrophoretically deposited photoresist.AlCu (Cu-0.5%),0.47-0.53 mum thick metal film is deposited on 3D structured silicon substrate to plate photoresist.By combining these two novel methods,metal (AlCu) traces of 75 mum line width and 150mum pitch (from top flat to down the slope) have been demonstrated on isotropically etched 350 mum deep trenches with 5-10% line width loss.